Something

pcm.ca0106 {
type hw
card 0
}

ctl.ca0106 {
type hw
card 0
}
pcm.!default {
slave.pcm surround51
slave.channels 6
type route
ttable.0.0 1
ttable.1.1 1
ttable.0.2 1
ttable.1.3 1
ttable.0.4 0.5
ttable.1.4 0.5
ttable.0.5 0.5
ttable.1.5 0.5
}